Method for lapping



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' SlohewQEoezfiiez a sneets sneet 8 Original Filed April 28, 1964 amvsmoa 3,391,501 METI-IGD FOR LAPPING Stephen A. Boettcher, Deerfield, llll., assignor to Speedfam Corporation, a corporation of Illinois Original application Apr. 28, 1964, Ser. N0. 363,196, now Patent No. 3,304,662, dated Feb. 21, 1967. Divided and this application Aug. 19, 1966, Ser. No. 591,047

11 Claims. (Cl. 51-281) ABSTRACT BE THE DISCLGSURE A method of lapping a plurality of work pieces on their One sides, inverting the work pieces as a group, and lapping them on their other sides.

This application is a division of my application Ser. No. 363,196, filed Apr. 28, 1964, now Patent No. 3,304,662, dated Feb. 21, 1967.

My present invention relates to a method for automatically lapping work pieces.

The general type of lapping machine with which the principles of my present invention may be incorporated includes an annular lapping disc, which is rotatably driven about a vertical axis, and on which work pieces are loaded in confined arrangement for the abrasive lapping of their surfaces by movement of the lapping disc relative to the work pieces. At the present time, work pieces to be lapped are manually moved onto the lapping disc and, after their surfaces have been lapped, are manually moved off of the lapping disc. When a group of work pieces are to be lapped on their opposite sides, the work pieces are first lapped on their one sides, then individually and manually turned over and lapped on their other sides. These procedures are time consuming and expensive.

It is an object of my present invention to provide a method for loading and unloading work pieces to and from the lapping disc of a lapping machine.

It is another object of my present invention to provide a method which includes the step of inverting work pieces which have been lapped on their one sides so that they are in position to be lapped on their other sides.

It is another object of my present invention to provide a method for lapping a plurality of adjacently located work pieces on their one sides until the latter are fiat, inverting the work pieces as a group, and lapping the work pieces on their other sides until the latter are parallel to the one sides thereof and the work pieces are of the desired thickness.

It is a further object of my present invention to provide a method for successively moving a plurality of adjncently located work pieces from a first loading station to a lapping disc where the work pieces are lapped on their one sides, moving the work pieces from the lapping disc to a first receiving station, inverting the work pieces and moving them from the first receiving station to a second loading station, moving the work pieces from the second loading station to the lapping disc where the work pieces are lapped on their other sides, and moving the work pieces from the lapping disc to a second receiving station.

It is a still further object of my present invention to provide a method for automatically loading and unloading substantially simultaneously at least two individual groups of adjacently located work pieces to and from a lapping machine.

Now in order to acquaint those skilled in the art with the manner using methods in accordance with the principles of my present invention, I shall describe in connection with the accompanying drawings, a preferred embodiment of my invention.

3,391,591 Patented July 9, 1968 "ice In the drawings:

FIGURE 1 is a perspective view of a lapping machine incorporating the principles of my present invention;

FIGURE 2 is a partial vertical sectional view, taken substantially along the line 2-2 in FIGURE 1, looking in the direction indicated by the arrows;

FIGURE 3 is a partial plan view, with portions of the upper framework removed, of the lapping machine of FIGURE 1;

FIGURE 4 is an enlarged fragmentary plan view of a portion of the apparatus of FIGURE 3 showing the power actuated arm means at the first loading station;

FIGURE 5 is a fragmentary elevational view of the power actuated arm means of FIGURE 4, taken substantially along the line 5-5 in FIGURE 4, locking in the direction indicated by the arrows;

FIGURE 6 is an enlarged fragmentary plan view of a portion of the apparatus of FIGURE 3 showing the inverting means, the power actuated engaging means at the first receiving station, and the power actuated pusher means at the second loading station;

FIGURE 7 is a vertical sectional view, taken substantially along the line 77 in FIGURE 6, looking in the direction indicated by the arrows;

FIGURE 8 is a vertical sectional view, taken substantially along the line 8-8 in FIGURE 6, looking in the direction indicated by the arrows;

FIGURE 9 is a fragmentary sectional view showing the parts of FIGURE 8 in an intermediate operative position;

FIGURE 10 is a fragmentary elevational view of the mechanism of FIGURE 6, taken substantially along the line 10-10 in FIGURE 6, looking in the direction indicated by the arrows;

FIGURE 11 is a vertical sectional view, taken substantially along the line 11-11 in FIGURE 6, looking in the direction indicated by the arrows;

FIGURE 12 is a vertical sectional view, taken substantially along the line 12-12 in FIGURE 6, looking in the direction indicated by the arrows;

FIGURE 13 is an enlarged fragmentary plan view of a portion of the apparatus of FIGURE 3 showing the power actuated arm means at the second receiving station;

FIGURE 14- is a fragmentary elevational view of the power actuated arm means of FIGURE 13, taken substantially along the line 14-14 in FIGURE 13, looking in the direction indicated by the arrows;

FIGURE 15 is a fragmentary elevational view of the power actuated arm means of FIGURES 13 and 14, taken substantially along the line 15-15 in FIGURE 14, looking in the direction indicated by the arrows; and

FIGURE 16 is a fragmentary elevational view of the latch mechanism of the power actuated arm means of FIGURE 13, taken substantially along the line 16-16 in FIGURE 13, looking in the direction indicated by the arrows.

Referring now to FIGURE 1, there is indicated generally by the reference numeral 10 a lapping machine incorporating the principles of my present invention. The lapping machine 11 comprises framework including a tubular base or housing 12 which provides support for a horizontal annular lapping disc 14. Selective rotation of the lapping disc 14 about a vertical axis is effected by suitable drive means (not shown) mounted within the housing 12. For details concerning one form of drive means for the lapping disc 14, reference may be made to United States Patent No. 2,869,294, issued Jan. 20, 1959. Suitably secured to the opposite sides of the housing 12 are the lower ends of vertical columns 16. Extending between the upper ends of the columns 16, above the lapping disc 14, is a horizontal bridge member 18 provided with transverse arms 20 which number four in the particular lapping machine herein disclosed. Mounted at the outer ends of each of the transverse arms is a vertical pneumatic piston and cylinder assembly indicated generally by the reference numeral 22. Each of the pneumatic assemblies 22 includes a cylinder 24 and a piston rod 26.

As shown in FIGURE 2, the lower ends of the piston rods 26 are secured to horizontal pressure plates 28. The pressure plates 28 fit, with slight clearance, within truing and retaining rings 30 engageable with the lapping disc 14. When the lapping disc 14 is rotated, the truing rings 30 rotate relative to the pressure plates 28 about the axes defined by the piston rods 26 whereby to dress the lapping disc 14 for maintenance of its planar condition. A plurality of lugs 32 are secured to the upper edges of each of the truing rings 30 and project radially inwardly and axially downwardly therefrom. When the pressure plates 28 are raised, they engage the free ends of the lugs 32 thereby raising the truing rings 30 from the lapping disc 14.

Raising of the pressure plates 28 and the associated truing rings 30 is effected by introducing air under pressure into the lower ends of the cylinders 24. Conversely, lowering of the pressure plates 28 and the associated truing rings 30 is effected by relieving the air pressure at the lower ends of the cylinders 24 and introducing air under pressure into the upper ends of the cylinders 24. When work pieces 34 are moved into the confines of the truing rings 30 below the pressure plates 28, air under pressure introduced into the upper ends of the cylinders 24 serves to impose a downward force or pressure on the pressure plates 28 and, in turn, on the work pieces 34. In accordance with the principles of my present invention, the work pieces 34 are confined within annular retaining members 36 which are receivable within the truing rings 30. The pressure plates 28 are each formed with an annular recess 38 to accommodate the retaining members 36.

Surrounding the lapping disc 14, as best shown in FIG- URE 3, is a planar staging table 42 which has notched out portions 44 at its opposite sides for receiving the vertical columns 16. The staging table 42 is supported from the housing 12 through the intervention of means (not shown) for slightly raising and lowering the table relative to the lapping disc 14 to facilitate loading and unloading of work pieces to and from the lapping disc 14. One form of raising and lowering means for a staging table is shown in United States Patent No. 2,912,799, issued Nov. 17, 1959. The staging table 42 is formed with a pair of lateral extension portions 46 that each serve as a first loading station. At each end of the staging table 42 I provide loading and unloading apparatus that cooperates with two of the pressure plates 28 and truing rings 30. Since the apparatus at the opposed ends of the staging table 42 are substantially identical in construction and operation, except that the components thereof are mounted in reverse relation, I shall describe in detail the apparatus at one end only of the staging table.

The power actuated arm means that I provide for moving a retaining member 36 having a plurality of work pieces 34 confined therein from the first loading station 46 onto the lapping disc 14 is supported from a generally vertical C-shaped bracket assembly 48. As shown in FIG- URES 4 and 5, the bracket assembly 48 is disposed about the adjacent column 16 and is suitably secured to the staging table 42. The bracket assembly 48 provides support for a vertical pivot shaft 50 and a horizontal support bar 52. Secured to the lower end of the pivot shaft 50 is the inner end of an arm member 54 having a downwardly offset arcuate outer end portion that overlies the staging table 42 closely adjacent thereto. Arcuate movement of the arm member 54 about the axis of the pivot shaft 50 is effected by means of a pneumatic piston and cylinder assembly indicated generally by the reference numeral 56. The pneumatic assembly 56 includes a cylinder 58 pivotally supported, at its forward end, by means of opposed pin members 60 journaled in a pair of vertically spaced strap members 62 secured to the upper and lower edges of the horizontal support bar 52. The pneumatic assembly 56 further includes a piston rod 64 having an outer yoke portion 66 pivotally mounted, as at 68, to the outer end of a lever 70 which, at its inner end, is secured to the pivot shaft 50 at the upper end thereof. The inner end of the arm member 54 and the lever '70 are interconnected by means of a web member 72.

When air under pressure is admitted to the rear end of the cylinder 58 the piston rod 64 is distended which causes clockwise pivotal movement of the lever 70 and arm member 54 from the position shown in solid lines in FIGURE 4 to the position shown in dot-dash lines. During such pivotal movement of the arm member 54, the retaining member 36 and work pieces 34 therein at the first loading station 46 are moved therefrom onto the lapping disc 14 where the work pieces may be lapped on their one sides. When air under pressure is admitted to the forward end of the cylinder 58, the piston rod 64 is retracted causing counterclockwise pivotal movement of the lever 70 and arm member 54 from the dot-dash line position to the solid line position.

In order that work pieces which have been lapped on their one sides may be turned over automatically so that they are in position to be lapped on their other sides, I provide inverting means indicated generally by the reference numeral in FIGURE 3. The inverting means 80, which i mounted in an extension portion 82 of the staging table 42, comprises a pair of platens 84 and 86 disposed side by side in initial horizontal positions and pivotally mounted along adjacent edges for swinging movement in a manner to be presently described. The extension portion 82 is rigidly secured to, and vertically movable with, the staging table 42.

Secured to the underside of the staging table extension 82, as shown in FIGURES 3 and 6, are a forward transverse frame member 88, a pair of rearwardly extending side frame members 90, and a pair of transverse laterally spaced frame members 92 and 94. The ends of the side frame members that project beyond the staging table extension 82 are interconnected by a rear transverse frame member 96. As shown in FIGURE 7, the transverse frame member-s 38 are interconnected intermediate of their ends by a strap member 98. Over-lying the strap member 98 is a rotatable shaft 100 which, at its forward end, is journaled in a bearing block 102 carried by the strap member 98, and, at its rearward end, is journaled in a bearing block 104 carried by the transverse frame member 94. Secured to the rotatable shaft 100, as shown in FIGURES 6, 7 and 8, are a pair of laterally spaced hinge members 106 which have flange portions 108 secured to the underside of the platen 86 and counterweight extension bars 109 normally underlying the platen 84. By reason of this mounting arrangement, the platen 86 pivots upon rotation of the shaft 100 and is counter-balanced by the extension bars 109. Arranged alternately with re spect to the hinge members 106, and rotatably mounted on the shaft 100, are a pair of hinge members 110 which have flange portions 112 secured to the underside of the platen 84 and counterweight extension bars 113 normally underlying the platen 86. Thus, the platen 84 is mounted for pivotal movement relative to the shaft 100 about the horizontal axis thereof and is counter-balanced by the extension bars 113.

As shown in FIGURES 6, 7 and 10, pivotal movement of the platens 84 and 86 is adapted to be effected by means of power actuated rack and pinion means mounted intermediate of the transverse frame members 92 and 94. Such means comprises a pinion 114 journaled on the shaft 100 and secured to a disc member 116 which, in turn, is secured to the adjacent hinge member 110, and a pinion 118 secured to the shaft 100. The pinions 114 and 118, at their lower sides, are respectively engaged by a pair of oppositely extending rack members 120 and 122. The rack members 120 and 122 are maintained in engagement with the pinions 114 and 118 by means of a pair of ball bearing assemblies 124 and a pair of side spacer members 126 supported by a rod 128 extending between and carried by the transverse frame members 92 and 94. The rack member 120 at its outer end is secured to the piston rod 130 of a pneumatic piston and cylinder assembly indicated generally at 132. The forward end of the cylinder 134 of the pneumatic assembly 132 is pivotally supported by means of opposed lateral pin member 136 journaled in depending plate members 138 secured to the transverse frame members 92 and 94. Similarly, the outer end of the rack member 122 is secured to the piston rod 140 of a pneumatic piston and cylinder assembly indicated at 142. The forward end of the cylinder 144 of the pneumatic assembly 142 is pivotally supported by means of opposed lateral pin members 146 journaled in a pair of depending plate members 148 secured to the transverse frame members 92 and 94.

When the pneumatic assembly 132 is actuated and the piston rod 130 thereof is distended, the rack member 120 is moved to the left as viewed in FIGURES 6 and thereby causing rotation of the pinion 114, disc member 116, and the adjacent hinge member 110, whereupon the platen 84 is pivoted in the direction of the platen 86 from the position shown in solid lines in FIGURE 8 to the position shown in dotted lines. Withdrawal of the piaton rod 130 effects movement of the rack member 120 to the right as viewed in FIGURES 6 and 10 thus effecting counter-rotation of the pinion 114, disc member 116, and the adjacent hinge member 110, whereupon the platen 84 is pivoted back to its initial horizontal position. When the pneumatic assembly 142 is actuated and the piston rod 140 thereof is distended, the rack member 122 is moved to the right as viewed in FIGURES 6 and 10 thus causing rotation of the pinion 118 and the shaft 100, whereupon the platen 86 is pivoted in the direction of the platen 84 from the position shown in solid lines in FIGURE 8 to the position shown in FIGURE 9. When the lpIStOH rod 140 is retracted the rack member 122 is moved back to the position shown in FIGURES 6 and 10, thus effecting counter-rotation of the pinion 118 and the shaft 100, whereupon the platen 86 is returned to its initial horizontal position. Stop plates 150 are secured to the staging table extension 82 adjacent the free sides of the platens 84 and 86 to prevent swinging movement of the latter below the :plane of the extension 82.

The platen 86 serves as a first receiving station for a retaining member 36 having a plurality of work pieces 34 confined therein that have had their one sides lapped on the lapping disc 14. To accomplish inversion of a retaining member and work pieces therein moved onto the platen 86, the platen 84 is swung in the direction of the platen 86 until the retaining member is confined between the platens 84 and 86, then the platens are together swung in the other direction until the platen 84 is returned to its initial horizontal position, and finally the platen 86 is returned to its initial horizontal position. To prevent the retaining member from interfering with the action of the hinge members 106 and 110 during inversion, a guide strip 152 (FIGURE 6) is secured to the surface of the platen 86.

The power actuated engaging means that I provide for moving a retaining member and work pieces therein from the lapping disc 14 onto the platen 86, as best shown in FIGURES 6 and 11, comprises a pneumatic piston and cylinder assembly indicated generally at 154. The pneumatic assembly 154 includes a cylinder 156 which, at its forward end, is secured to plate means 158 carried by the transverse frame member 94, and, at its rearward end, is secured to the transverse frame member 96. The piston rod 160 of the pneumatic assembly 154 serves to actuate latch mechanism indicated generally at 162. The latch mechanism 162 comprises a T-shaped support member 164 secured to the outer end of the piston rod 160. A pair of rollers 166 are mounted at the outer ends of the lateral arms of the T-shaped support member 164 and serve to facilitate movement of the latter over the staging table extension 82, the platen 86, and the staging table 42. Extending transversely across a recess formed in the T- shaped support member 164 is a pin member 168 upon which is pivotally mounted a pair of laterally spaced pawl members 170. Secured to the forward ends of the pawl members 170 are latch members 172 having tongue portions 173. Arranged within the support member 164 are springs 174 that engage and serve to bias the pawl members 170 and latch members 172 in a counterclockwise direction as viewed in FIGURE 11. Secured to the staging table extension 82 adjacent the forward end of the cylinder 156 are a pair of laterally spaced block members 176 having laterally facing flange portions that define camming surfaces 178 on their undersides. When the pawl members 170 engage the camming surfaces 178, the latch members 172 are pivoted to the unlatching position shown in FIGURE 10 with the springs 174 being thereby compressed.

When the pneumatic assembly 154 is actuated and the piston rod is distended, the latch mechanism 162 is moved forwardly across the staging stable extension 82, the platen 86 and the staging table 42. As soon as the pawl members are moved out of engagement with the camming surfaces 178 of the block members 176, the springs 174 bias the latch members 172 downwardly to their latching poistions. As the latch members 172 approach a retaining member 36 on the lapping disc 14, the tongue portions 173 ride over the retaining member 36 and drop down into engagement with the inner annular surface thereof. When the piston rod 160 is now retracted, the latch mechanism 162 serves to pull the retaining member 36 and work pieces therein off of the lapping disc 14 and onto the platen 86. As the piston rod 160 approaches full retraction, the pawl members 170 engage the camming surfaces 17 8 of the block members 176 causing the latch members 172 to pivot upwardly and the tongue portions 173 to be moved out of engagement with the retaining member 36 thereby releasing the latter.

The platen 84 serves as a second loading station, and power actuated pusher means is provided for moving a retaining member 36 having a plurality of work pieces confined therein (which have been lapped on their one sides and inverted) from the platen 84 across the staging table 42 onto the lapping disc 14. Such pushing means, as shown in FIGURES 6 and 12, comprises a pneumatic piston and cylinder assembly indicated generally at 184. The pneumatic assembly 184 includes a cylinder 186 which, at its forward end, is secured to plate means 188 carried by the transverse frame member 94, and, at its rearward end is secured to the transverse frame member 96. The outer end of the piston rod 190 of the pneumatic assembly 184 is secured to a generally T-shaped frame member 192 supported on a pair of rollers 194 and having a recessed forward face 196. Upon actuation of the pneumatic assembly 184, the piston rod 190 is distended thereby causing forward movement of the T-shaped frame member 192 whereby a retaining member 36 and work pieces therein may be moved from the platen 84 across the staging table 42 onto the lapping disc 14. Upon retraction of the piston rod 190, the T-shaped pusher member 192 is returned to the position shown in FIGURES 6 and 12.

Referring again to FIGURES 1 and 3, there is shown along side of the staging table 42, opposite the first loading station 46, a second receiving station in the form of a conveyor belt 204 supported on framework 205. Power actuated arm means is provided at this station for moving a retaining member 36 and work pieces therein (which have been lapped on their oppoiste sides) off of the lapping disc 14 across the staging table 42 and onto the conveyor belt 204. As best shown in FIGURES 13, 14 and 15, support for the power actuated arm means is provided by a generally C-shaped frame assembly 206 which comprises a pair of vertically spaced bar members 208, rearwardly extending side flange members 210, and foot members 212 suitably secured to the staging table 42 at the sides of the adjacent column 16. A generally L- shaped arm member 214 is pivotally mounted at the end of its shorter leg on the intermediate portion of a vertical rod 216 secured within the bar members 208. To gain rigidity an angle bracket 217 is provided with one leg being secured to the arm member 214 and with the other leg being pivotally mounted on the upper end of the rod 216. Pivotal movement of the arm member 214 about the axis of the rod 216 is effected by means of a pneumatic piston and cylinder assembly indicated generally at 218. The cylinder 220 of the pneumatic assembly 218 is pivotally supported at its forward end, by means of opposed pin members 222 journaled in the ends of a pair of vertically spaced strap members 224 secured to brackets 226 carried by the side flange members 210. The outer end of the piston rod 228 of the pneumatic assembly 218 is pivotally mounted by means of a pin member 230 in a boss member 232 carried by the arm member 214 intermediate of the ends thereof.

When the pneumatic assembly 218 is actuated and the piston rod 228 is distended, the arm member 214 is pivoted along an arcuate path from the position shown in dotted lines in FIGURE 13 to the position shown in solid lines. Upon retraction of the piston rod 228, the arm member 214 is returned from the solid line position shown in FIGURE 12 to the dotted line position. The arm member 214 is spaced vertically above the staging table 42 and carries at its outer end latch mechanism indicated generally by the reference numeral 234. The latch mechanism 234, as shown in FIGURES 14 and 16, comprises a depending support member 236 which is provided with laterally spaced recesses 238 in its underside. Pivotally mounted on a horizontal pin 240 extending transversely of the recesses 238 are a pair of latch members 242 having tongue portions 243. The latch members 242, due to gravity, normally assume the position shown in dotted lines in FIGURE 16. When the arm member 214 is pivoted to the position shown in solid lines in FIGURE 13, the tongue portions 243 of the latch members 242 ride over the edge of the retaining member 36 and engage the inner annular surface thereof. Then, as the arm member 214 is pivoted back to the dotted line position shown in FIGURE 13, the engaged retaining member 36 is moved off of the lapping disc 14 across the staging table 42 and on to the conveyor belt 204. Means for effecting release of the latch members 242 from engagement with the retaining member 36 comprises a support member 244 secured at its inner end to the lower strap member 224 and carrying at its outer end a depending block member 246 having a camming surface 248 formed thereon. As the retaining member 36 is pulled onto the conveyor belt 204, the projection ends of the latch members 242 engage the camming surface 248 and are pivoted in a clockwise direction from the dotted line position shown in FIGURE 16 to the solid line position, whereby the tongue portions 243 are withdrawn from engagement with the retaining member 36.

I will now describe the steps involved in lapping the opposite sides of a plurality of adjacently confined work pieces with the above described apparatus in accordance with the principles of my present invention. At the beginning of operations, the various power actuated components of the loading and unloading mechanism assume the positions shown in FIGURE 3. A retaining member 36 is first placed on the lateral extension portion 46 of the staging table 42 at the first loading station, and the retaining member 36 is then filled with unlapped work pieces. Preferably, the retaining member 36 has a height greater than that of the work pieces therein so that the retaining member may be conveniently engaged by the latch mechanisms .162 and 234. After the pressure plates 28 and truing rings 30 have been raised from the lapping disc 14, the arm member 54 is pivoted from the solid line position shown in FIGURES 3 and 4 to the dotted line position shown in FIGURE 4, thereby pushing the retaining member 36 and work pieces therein onto the lapping disc 14 beneath the adjacent first pressure plate 28 at a first lapping station. After the arm member 54 has been pivoted back to the solid line position, the pressure plates 28 and truing rings 30 are moved downwardly into engagement respectively with the work pieces and the lapping disc. At this time, the lapping disc 14 is rotated for lapping the one sides of the work pieces fiat.

At the completion of this lapping operation, the pressure plates 28 and truing rings 30 are raised, the latch mechanism 162 is moved forwardly into engagement with the retaining member, and the retaining member is then pulled ofi of the lapping disc 14, across the staging table 42, and onto the platen 86 of the inverting means at the first receiving station. To effect inversion or rotation through of the work pieces that have been lapped on their one sides, the platen 84 of the inverting means 80 is first pivotedin one direction toward the platen 86 from the solid line position shown in FIGURE 8 to the dotted line position, whereupon the retaining member 36 and work pieces therein are confined between the platens 84 and 86. Then, through simultaneous actuation of the pneumatic assemblies 132 and 142, the platens 84 and 86 are pivoted conjointly in the other direction until the platen 84 is returned to its initial horizontal position whereupon the retaining member and work pieces therein are inverted with the lapped sides of the work pieces facing upwardly. An intermediate pivotal position of the platens 84 and 86 is shown in dot-dash lines in FIGURE 8, while the position of the platens 84 and 86 at the completion of inversion is shown in FIGURE 9. During this step of inversion, the retaining member and work pieces therein are moved from the first receiving station or platen 86 to the second loading station or platen 84. To complete the cycle of inversion, the platen 86 is pivoted back to its initial horizontal position shown in solid lines in FIG- URE 8.

With the pressure plates 28 and truing rings 30 in a raised position, the pusher member 192 is moved forwardly for moving the retaining member and work pieces off of the platen 84, across the staging table 42, and onto the lapping disc 14 beneath the adjacent second pressure plate 28 at a second lapping station. Upon retraction of the pusher member 192, the pressure plates 28 and truing rings 30 are again lowered into engagement respectively with the work pieces and the lapping disc. As the lapping disc 14 is rotated, the opposite sides of the work pieces are lapped parallel to their one sides. Upon completion of this lapping operation, the pressure plate 28 and truing rings 30 are raised, and the arm member 214 is pivoted from the solid line position shown in FIGURE 3 to the solid line position shown in FIGURE 13 until the latch mechanism 234 engages the retaining member 36. Finally, as the arm member 214 is returned to the solid line position shown in FIGURE 3, the retaining member and work pieces therein are moved off of the lapping disc 14, across the staging table 42, and onto the conveyor belt 204 that serves as a second receiving station. This completes the description of the path followed by one group of work pieces confined within a retaining member.

In the normal sequence of operation, retaining members and work pieces therein are successively introduced into the lapping cycle. Therefore, at any given time, except at the very initiation or termination of operations, there will be several groups of work pieces in the lapping apparatus each at a different location and in a different stage of the lapping cycle. As one illustration, at one point in the lapping cycle, one retaining member and work pieces therein are at the first lapping station and another retaining member and work pieces therein are at the second lapping station. As the work pieces at the first lapping station are having their one sides lapped flat, and the work pieces at the second lapping station are having their other sides lapped parallel to their one sides, a retaining member having work pieces lapped on their one sides and confined therein is inverted and moved from the platen 86 or first receiving station to the platen 84 or the second loading station, and still another retaining member is filled with unlapped work pieces at the first loading station 46. Upon completion of lapping of the work pieces on the lapping disc 14, the pressure plates 28 and truing rings 30 are raised, Then the latch mechanisms 162 and 234 are moved substantially simultaneously in the direction of the lapping disc until they engage the pair of retaining members thereon. Upon return of the latch mechanisms 162 and 234 to their normal positions shown in FIGURE 3, the retaining member having work pieces lapped on their one sides and confined therein is moved onto the platen 85 or first receiving station, and the retaining member having work pieces lapped on their opposite sides and confined therein is moved onto the conveyor belt 204 or second receiving station. Next, the arm member 54 is actuated for moving the retaining member having unlapped work pieces therein from the first loading station 46 to the first lapping station. Substantially simultaneously, the pusher member 192 is actuated for moving the inverted retaining member and work pieces therein from the platen 84 or second loading station to the second lapping station. The described lapping cycle is then repeated. Thus, in the manner explained, two individual groups of adjacently located work pieces are substantially simultaneously loaded and unloaded to and from the lapping disc 14. It will be appreciated that when loading and unloading apparatus embodying the principles of my present invention is used at both ends of the staging table 42, four individual groups of adjacently located work pieces may be substantially simultaneously loaded and unloaded to and from the lapping disc 14.

At the first lapping station, the one sides of the work pieces are lapped flat; at the second lapping station, the other sides of the work pieces are lapped parallel to the one sides thereof, and the work pieces are lapped to the desired thickness. Because these two operations are different, a greater amount of stock may be removed from the workpieces at the second lapping station than from the work pieces at the first lapping station. Even though the amount of stock removed from the work pieces at the two lapping stations may be unequal, it is desirable that the time required to remove necessary stock from the work pieces at these stations be maintained substantially equal. Therefore, to attain this objective, and in accordance with the principles of my present invention, the pressure applied to the work pieces being lapped at the second lapping station may be different in magnitude than the pressure applied to the work pieces being lapped at the first lapping station.

All of the pneumatic assemblies of the above described apparatus are supplied air under pressure from a conventional pump and through a conventional control system (not shown), Suitable known air regulators are incorporated in the control system to control the pressure of the air delivered to the various pneumatic assemblies, and a conventional electric circuit, including limit swtches arranged at various locations on the described apparatus, is employed to control the proper sequence of operation of the air regulators or valves associated with the pneumatic assemblies. Those skilled in the art will readily appreciate that a hydraulic system may be used in place of all or part of the pneumatic system described herein.

To accommodate unevenness in the surfaces of unlapped work pieces, a pad 250 of felt or the like is preferably interposed between the pressure plate 28 and the work pieces 34 at the first lapping station as shown in FIGURE 2. Such a pad is unnecessary at the second lapping station because the sides of the work pieces that bear against the pressure plate 28, which serves as a hard reference member, have been lapped flat. To minimize space requirements, it is to be noted that the power actuated arm members 54 and 214 are each arranged to move a retaining member and work pieces therein along an arcuate path. However, the latch mechanism 162 and pusher 192 must have straight line motion because a retaining member and work pieces therein must be moved onto and oil of the inverting platens 84 and 86 along a path parallel to the hinge axis thereof due to the inter ference of the projecting portions of the hinge members.

While I have shown and described what I believe to be a preferred embodiment of the method of my present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of my invention.

I claim:

1. A method of lapping a plurality of work pieces in a lapping machine having a lapping disc and at least one truing ring with a pressure plate therein elevated vertically above the lapping disc, comprising the steps of moving a retaining member having a plurality of work pieces confined therein onto the lapping disc beneath the pressure plate, vertically lowering the truing ring and pressure plate respectively into engagement with the lapping disc and work pieces, rotating the lapping disc for lapping the sides of the work pieces in contact with the lapping disc, vertically raising the truing ring and pressure plate from the lapping disc and work pieces, and moving the retaining member and work pieces therein olf of the lapping disc.

2. A method of lapping the opposite sides of a plurality of work pieces on a lapping disc, comprising the steps of moving a retaining member having a plurality of work pieces movable relative to each other and loosely confined therein onto the lapping disc, rotating the lapping disc for lapping the one sides of the work pieces in contact with the lapping disc, moving the retaining member and work pieces therein off of the lapping disc, inverting the retaining member and work pieces therein, moving the inverted retaining member and work pieces therein onto the lapping disc, rotating the lapping disc for lapping the other sides of the work pieces in contact with the lapping disc, and moving the retaining member and work pieces therein off of the lapping disc.

3. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a plurality of adjacently confined work pieces as a group onto the lapping disc beneath one of the pressure plates, lowering the said one pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, rotating the lapping disc for lapping the one sides of the work pieces in contact with the lapping disc, raising the said one pressure plate and associated truing ring from the work pieces and lapping disc, moving the plurality of adjacently confined work pieces as a group off of the lapping disc, inverting the plurality of adjacently confined work pieces as a group, moving the plurality of inverted adjacently confined work pieces as a group onto the lapping disc beneath the other of the pressure plates, lowering the said other pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, rotating the lapping disc for lapping the other sides of the work pieces in contact with the lapping disc, raising the said other pressure plate and associated truing ring from the work pieces and lapping disc, and moving the plurality of adjacently confined work pieces as a group off of the lapping disc.

4. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a plurality of adjacently confined work pieces as a group onto the lapping disc beneath one of the pressure plates, lowering the said one pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, applying pressure of a predetermined magnitude on the said one pressure plate, rotating the lapping disc for lapping the one sides of the work pieces in contact with the lapping disc until the said one sides of the work pieces are ilat, raising the said one pressure plate and associated truing ring from the work *ieces and lapping disc, moving the plurality of adjacently confined work pieces as a group off of the lapping disc, inverting the plurality of adjacently confined work pieces as a group, moving the plurality of inverted adjacently confined work pieces as a group onto the lapping disc beneath the other of the pressure plates, lowering the said other pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, applying pressure on the said other pressure plate of a higher magnitude than the pressure applied to the said one pressure plate, rotating the lapping disc for lapping the other sides of the work pieces in contact with the lapping disc until the said other sides of the work pieces are parallel to the said one sides thereof, raising the said other pressure plate and associated truing ring from the work pieces and lapping disc, and moving the plurality of adjacently confined work pieces as a group off of the lapping disc.

5. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a retaining member having a plurality of work pieces confined therein onto the lapping disc beneath one of the pressure plates, lowering the said one pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, rtating the lapping disc for lapping the one sides of the work pieces in contact with the lapping disc, raising the said one pressure plate and associated truing ring from the work pieces and lapping disc, moving the retaining member and work pieces therein ofi of the lapping disc, inverting the retaining member and work pieces therein, moving the inverted retaining member and work pieces therein onto the lapping disc beneath the other of the pressure plates, lowering the said other pressure plate and associated truing ring respectively into engagement with the work pieces and lapping disc, rotating the lapping disc for lapping the other sides of the work pieces in contact with the lapping disc, raising the said other pressure plate and associated truing ring from the work pieces and lapping disc, and moving the retaining member and work pieces therein off of the lapping disc.

6. A method of lapping the opposite sides of a plurality of work pieces on a lapping disc, comprising the steps of moving a first group of adjacently confined work pieces from a first loading station onto the lapping disc, substantially simultaneously moving a second group of adjacently confined work pieces from a second loading station onto the lapping disc, rotating the lapping disc for lapping the sides of the said first and second groups of work pieces in contact with the lapping disc, inverting and moving a third group of adjacently confined work pieces from a first receiving station to the said second loading station while the lapping disc is rotating, moving the said first group of work pieces from the lapping disc to the said first receiving station, and substantially simultaneously moving the said second group of work pieces from the lapping disc to a second receiving station.

7, A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a first group of adjacently confined work pieces from a first loading station onto the lapping disc beneath one of the pressure plates, substantially simultaneously moving a second group of adjacently confined work pieces from a second loading station onto the lapping disc beneath the other of the pressure plates, lowering both of the pressure plates and associated truing rings respectively into engagement with the said first and second groups of work pieces and the lapping disc, rotating the lapping disc for lapping the sides of the said first and second groups of work pieces in contact with the lapping disc, inverting and moving a third group of adjacently confined work pieces from a first receiving station to the said second loading station while the lapping disc is rotating, raising both of the pressure plates and associated truing rings from the said first and second groups of work pieces and lapping disc, moving the said first group of work pieces from the lapping disc to the said first receiving station, and substantially simultaneously moving the said second group of work pieces from the lapping disc to a second receiving station.

8. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a first retaining member having a plurality of work pieces confined therein from a first loading station onto the lapping disc beneath one of the pressure plates, substantially simultaneously moving a second retaining member having a plurality of work pieces confined therein from a second loading station onto the lapping disc beneath the other of the pressure plates, lowering both of the pressure plates and associated truing rings respectively into engagement with the work pieces within the first and second retaining members and the lapping disc, rotating the lapping disc for lapping the sides of the work pieces in contact with the lapping disc, inverting and moving a third retaining member having a plurality of work pieces confined therein from a first receiving station to the said second loading station while the lapping disc is rotating, raising both of the pressure plates and associated truing rings from the work pieces within the said first and second retaining members and lapping disc, moving the said first retaining member and work pieces therein from the lapping disc to the said first receiving station, and substantially simultaneously moving the said second retaining member and work pieces therein from the lapping disc to a second receiving station.

9. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving a first retaining member havig a plurality of unlapped work pieces confined therein from a first loading station onto the lapping disc beneath one of the pressure plates, substantially simultaneously moving a second retaining member having a plurality of work pieces lapped on their upper sides and confined therein from a second loading station onto the lapping disc beneath the other of the pressure plates, lowering both of the pressure plates and associated truing rings respectively into engagement with the Work pieces within the said first and second retaining members and the lapping disc, applying pressure of a predetermined magnitude on the said one pressure plate and applying pressure on the said other pressure plate of a higher magnitude than the pressure applied to the said one pressure plate, rotating the lapping disc for lapping the sides of the work pieces in contact with the lapping disc, inverting and moving a third retaining member having a plurality of work pieces lapped on their upper sides and confined therein from a first receiving station to the said second loading station whereby to face their lapped sides upwardly while the lapping disc is rotating, raising both of the pressure plates and associated truing rings from the work pieces within the said first and second retaining members and lapping disc, moving the said first retaining member and work pieces therein from the lapping disc to the said first receiving station, and substantially simultaneously moving the said second retaining member and work pieces therein from the lapping disc to a second receiving station.

10. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of moving along an arcuate path a first retaining member having a plurality of work pieces confined therein from a first loading station located adjacent the side of one of the pressure plates onto the lapping disc beneath the said one pressure plate, substantially simultaneously moving along a straight line path a second retaining member having a plurality of work pieces confined therein from a second loading station located forwardly of the other pressure plate onto the lapping disc beneath the said other pressure plate, lowering both of the pressure plates and associated truing rings respectively into engagement with the work pieces within the said first and second retaining members and the lapping disc, rotating the lapping disc -for lapping the sides of the work pieces in contact with the lapping disc, inverting and moving a third retaining member having a plurality of work pieces confined therein from a first receiving station located forwardly of the said one pressure plate to the said second loading station while the lapping disc is rotating, raising both of the pressure plates and associated truing rings from the Work pieces within the first and second retaining members and lapping disc, moving along a straight line path the said first retaining member and work pieces therein from the lapping disc to the said first receiving station, and substantially simultaneously moving along an arcuate path the said second retaining member and work pieces therein from the lapping disc to a second receiving station located adjacent the side of the said other pressure plate.

11. A method of lapping the opposite sides of a plurality of work pieces in a lapping machine having a lapping disc and at least two truing rings each with a pressure plate therein spaced above the lapping disc, comprising the steps of pushing along an arcuate path a first retaining member having a plurality of unlapped Work pieces confined therein from a first loading station located adjacent the side of one of the pressure plates onto the lapping disc beneath the said one pressure plate, substantially simultaneously pushing along a straight line path a second retaining member having a plurality of work pieces lapped on their upper sides and confined therein from a second loading station located forwardly of the other pressure plate onto the lapping disc beneath the said other pressure plate, lowering both of the pressure plates and associated truing rings respectively into engagement with the Work pieces within the said first and second retaining members and the lapping disc, applying pressure of a predetermined magnitude on the said one pressure plate and applying pressure on the said other pressure plate of a higher magnitude than the pressure applied to the said one pressure plate, rotating the lapping disc for lapping the sides of the work pieces in contact with the lapping disc, inverting and moving a third retaining member having a plurality of work pieces lapped on their one sides and confined therein from a first receiving station located forwardly of the said one pressure plate to the said second loading station whereby to face their lapped sides upwardly While the lapping disc is rotating, raising both of the pressure plates and associated truing rings from the work pieces Within the said first and second retaining members and lapping disc, pulling along a straight line path the said first retaining member and work pieces therein from the lapping disc to the said first receiving station, and substantially simultaneously pulling along an arcuate path the said second retaining member and work pieces therein from the lapping disc to a second receiving station located adjacent the side of the said other pressure plate.

References Cited UNITED STATES PATENTS 1,360,054 11/1920 Sweet 335-289 1,371,854 3/1921 Buck 51-134 X 1,528,993 3/1925 Samuel 51-134 X 1,548,562 8/1925 Spencer 51-134 1,763,647 6/1930 Danner 51-131 2,565,590 8/1951 Bullard 51-131 2,627,144 2/1953 Roshang 51-131 X 2,821,818 2/1958 McGee et a1. 51-134 2,869,294 1/1959 Boettcher et a1. 51-266 2,883,803 4/1959 Stead 51-131 2,912,799 11/1959 Boettcher 51-131 LESTER M. SWINGLE, Primary Examiner. 

